/*
 * Copyright 2017 ~ 2025 the original author or authors. James Wong <jameswong1376@gmail.com>>
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package com.wl4g.infra.common.remoting.uri;

import java.io.ByteArrayInputStream;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.Reader;
import java.nio.CharBuffer;
import java.nio.charset.Charset;
import java.nio.charset.StandardCharsets;

import javax.annotation.Nullable;
import com.wl4g.infra.common.io.ByteStreamUtils;
import com.wl4g.infra.common.lang.ObjectUtils2;
import com.wl4g.infra.common.remoting.ClientHttpResponse;
import com.wl4g.infra.common.remoting.RestClient.ResponseErrorHandler;
import com.wl4g.infra.common.remoting.exception.HttpClientErrorException;
import com.wl4g.infra.common.remoting.exception.HttpServerErrorException;
import com.wl4g.infra.common.remoting.exception.UnknownHttpStatusCodeException;
import com.wl4g.infra.common.remoting.standard.HttpHeaders;
import com.wl4g.infra.common.remoting.standard.HttpMediaType;
import com.wl4g.infra.common.remoting.standard.HttpStatus;

/**
 * Default implementation of the {@link ResponseErrorHandler} interface.
 *
 * <p>
 * This error handler checks for the status code on the
 * {@link ClientHttpResponse}: Any code with series
 * {@link HttpStatus.Series#CLIENT_ERROR} or
 * {@link HttpStatus.Series#SERVER_ERROR} is considered to be an error; this
 * behavior can be changed by overriding the {@link #hasError(HttpStatus)}
 * method. Unknown status codes will be ignored by
 * {@link #hasError(ClientHttpResponse)}.
 *
 * @see RestTemplate#setErrorHandler
 */
public class DefaultResponseErrorHandler implements ResponseErrorHandler {

    /**
     * Delegates to {@link #hasError(HttpStatus)} (for a standard status enum
     * value) or {@link #hasError(int)} (for an unknown status code) with the
     * response status code.
     * 
     * @see ClientHttpResponse#getRawStatusCode()
     * @see #hasError(HttpStatus)
     * @see #hasError(int)
     */
    @Override
    public boolean hasError(ClientHttpResponse response) throws IOException {
        int rawStatusCode = response.getRawStatusCode();
        HttpStatus statusCode = HttpStatus.resolve(rawStatusCode);
        return (statusCode != null ? hasError(statusCode) : hasError(rawStatusCode));
    }

    /**
     * Template method called from {@link #hasError(ClientHttpResponse)}.
     * <p>
     * The default implementation checks {@link HttpStatus#isError()}. Can be
     * overridden in subclasses.
     * 
     * @param statusCode
     *            the HTTP status code as enum value
     * @return {@code true} if the response indicates an error; {@code false}
     *         otherwise
     * @see HttpStatus#isError()
     */
    protected boolean hasError(HttpStatus statusCode) {
        return statusCode.isError();
    }

    /**
     * Template method called from {@link #hasError(ClientHttpResponse)}.
     * <p>
     * The default implementation checks if the given status code is
     * {@link HttpStatus.Series#CLIENT_ERROR CLIENT_ERROR} or
     * {@link HttpStatus.Series#SERVER_ERROR SERVER_ERROR}. Can be overridden in
     * subclasses.
     * 
     * @param unknownStatusCode
     *            the HTTP status code as raw value
     * @return {@code true} if the response indicates an error; {@code false}
     *         otherwise
     * @since 4.3.21
     * @see HttpStatus.Series#CLIENT_ERROR
     * @see HttpStatus.Series#SERVER_ERROR
     */
    protected boolean hasError(int unknownStatusCode) {
        HttpStatus.Series series = HttpStatus.Series.resolve(unknownStatusCode);
        return (series == HttpStatus.Series.CLIENT_ERROR || series == HttpStatus.Series.SERVER_ERROR);
    }

    /**
     * Delegates to {@link #handleError(ClientHttpResponse, HttpStatus)} with
     * the response status code.
     * 
     * @throws UnknownHttpStatusCodeException
     *             in case of an unresolvable status code
     * @see #handleError(ClientHttpResponse, HttpStatus)
     */
    @Override
    public void handleError(ClientHttpResponse response) throws IOException {
        HttpStatus statusCode = HttpStatus.resolve(response.getRawStatusCode());
        if (statusCode == null) {
            String message = getErrorMessage(response.getRawStatusCode(), response.getStatusText(), getResponseBody(response),
                    getCharset(response));
            throw new UnknownHttpStatusCodeException(message, response.getRawStatusCode(), response.getStatusText(),
                    response.getHeaders(), getResponseBody(response), getCharset(response));
        }
        handleError(response, statusCode);
    }

    /**
     * Return error message with details from the response body, possibly
     * truncated:
     * 
     * <pre>
     * 404 Not Found: [{'id': 123, 'message': 'my very long... (500 bytes)]
     * </pre>
     */
    private String getErrorMessage(int rawStatusCode, String statusText, @Nullable byte[] responseBody,
            @Nullable Charset charset) {

        String preface = rawStatusCode + " " + statusText + ": ";
        if (ObjectUtils2.isEmpty(responseBody)) {
            return preface + "[no body]";
        }

        charset = charset == null ? StandardCharsets.UTF_8 : charset;
        int maxChars = 200;

        if (responseBody.length < maxChars * 2) {
            return preface + "[" + new String(responseBody, charset) + "]";
        }

        try {
            Reader reader = new InputStreamReader(new ByteArrayInputStream(responseBody), charset);
            CharBuffer buffer = CharBuffer.allocate(maxChars);
            reader.read(buffer);
            reader.close();
            buffer.flip();
            return preface + "[" + buffer.toString() + "... (" + responseBody.length + " bytes)]";
        } catch (IOException ex) {
            // should never happen
            throw new IllegalStateException(ex);
        }
    }

    /**
     * Handle the error in the given response with the given resolved status
     * code.
     * <p>
     * The default implementation throws an {@link HttpClientErrorException} if
     * the status code is {@link HttpStatus.Series#CLIENT_ERROR CLIENT_ERROR},
     * an {@link HttpServerErrorException} if it is
     * {@link HttpStatus.Series#SERVER_ERROR SERVER_ERROR}, or an
     * {@link UnknownHttpStatusCodeException} in other cases.
     * 
     * @since 5.0
     * @see HttpClientErrorException#create
     * @see HttpServerErrorException#create
     */
    protected void handleError(ClientHttpResponse response, HttpStatus statusCode) throws IOException {
        String statusText = response.getStatusText();
        HttpHeaders headers = response.getHeaders();
        byte[] body = getResponseBody(response);
        Charset charset = getCharset(response);
        String message = getErrorMessage(statusCode.value(), statusText, body, charset);

        switch (statusCode.series()) {
        case CLIENT_ERROR:
            throw HttpClientErrorException.create(message, statusCode, statusText, headers, body, charset);
        case SERVER_ERROR:
            throw HttpServerErrorException.create(message, statusCode, statusText, headers, body, charset);
        default:
            throw new UnknownHttpStatusCodeException(message, statusCode.value(), statusText, headers, body, charset);
        }
    }

    /**
     * Determine the HTTP status of the given response.
     * 
     * @param response
     *            the response to inspect
     * @return the associated HTTP status
     * @throws IOException
     *             in case of I/O errors
     * @throws UnknownHttpStatusCodeException
     *             in case of an unknown status code that cannot be represented
     *             with the {@link HttpStatus} enum
     * @since 4.3.8
     * @deprecated as of 5.0, in favor of
     *             {@link #handleError(ClientHttpResponse, HttpStatus)}
     */
    @Deprecated
    protected HttpStatus getHttpStatusCode(ClientHttpResponse response) throws IOException {
        HttpStatus statusCode = HttpStatus.resolve(response.getRawStatusCode());
        if (statusCode == null) {
            throw new UnknownHttpStatusCodeException(response.getRawStatusCode(), response.getStatusText(), response.getHeaders(),
                    getResponseBody(response), getCharset(response));
        }
        return statusCode;
    }

    /**
     * Read the body of the given response (for inclusion in a status
     * exception).
     * 
     * @param response
     *            the response to inspect
     * @return the response body as a byte array, or an empty byte array if the
     *         body could not be read
     * @since 4.3.8
     */
    protected byte[] getResponseBody(ClientHttpResponse response) {
        try {
            return ByteStreamUtils.copyToByteArray(response.getBody());
        } catch (IOException ex) {
            // ignore
        }
        return new byte[0];
    }

    /**
     * Determine the charset of the response (for inclusion in a status
     * exception).
     * 
     * @param response
     *            the response to inspect
     * @return the associated charset, or {@code null} if none
     * @since 4.3.8
     */
    @Nullable
    protected Charset getCharset(ClientHttpResponse response) {
        HttpHeaders headers = response.getHeaders();
        HttpMediaType contentType = headers.getContentType();
        return (contentType != null ? contentType.getCharset() : null);
    }

}